Sensitive paint

While it was generally safe to clean the paint surfaces, the conservators discovered that many areas containing red and green pigments were fragile: even the mildest of cleaning solutions applied too liberally could remove original pigment. The underbound nature of the paint films caused this sensitivity. In addition, the wax coating applied during the 1953 restoration had penetrated the paint films, making the paint even more sensitive.

During testing, this swab revealed a particularly sensitive area of paint. Conservators stopped the cleaning to reassess
their methods. (1999 photo)